boolean suppressGetSupertype() default false;
  }

  private @Nullable Method method = null;

  /** Call this in a {@link TestSubtype} public method asserting subtype relationship. */
  final <T> T isSubtype(T sub) {
    Type returnType = method.getGenericReturnType();
    Type paramType = getOnlyParameterType();
    TestSubtype spec = method.getAnnotation(TestSubtype.class);

    boolean suppressGetSupertype() default false;
  }

  private @Nullable Method method = null;

  /** Call this in a {@link TestSubtype} public method asserting subtype relationship. */
  final <T> T isSubtype(T sub) {
    Type returnType = method.getGenericReturnType();
    Type paramType = getOnlyParameterType();
    TestSubtype spec = method.getAnnotation(TestSubtype.class);